Cemiplimab in advanced periocular conjunctival and cutaneous squamous cell carcinoma: a United Kingdom case series.

Purpose: To evaluate the real-world efficacy, safety, and outcomes of cemiplimab for advanced periocular conjunctival and cutaneous squamous cell carcinoma (SCC).

Methods: Retrospective case series of adults treated with cemiplimab for periocular conjunctival or cutaneous SCC at Moorfields Eye Hospital (2021-2025).

Results: We included 9 patients (mean age 66, range 43-79; 56% female; 78% Caucasian). Prior treatments included surgery (44%), radiotherapy (22%), and one exenteration. Tumour origin was conjunctival (56%), cutaneous (33%), or unknown (11%). 8 (89%) showed orbital invasion, including 2 with intracranial spread. Cemiplimab was indicated when surgery was refused or as palliative treatment in cases not amenable to localized treatment. Mean cemiplimab duration was 12.3 months (range 2.1-36.4). Immune-related adverse events included grade 2 hypothyroidism (n = 2, continued therapy) and grade 2 hepatitis (n = 1, discontinued). Complete and partial responses were seen in 22% and 33%, respectively; 44% progressed. No significant difference in response was observed between conjunctival and cutaneous SCC (p = 1.00). 2 patients (22%) underwent exenteration after starting treatment. Average total follow-up was 50.8 months (range 17.4-130.6). One recurrence occurred 12 months after treatment cessation; no new metastases were reported during follow-up. Two patients died from unrelated causes.

Conclusion: To our knowledge, this is the largest single case series of cemiplimab used in conjunctival SCC. Our results underscore the potential of cemiplimab as globe-sparing and vision-preserving treatment in advanced periocular conjunctival and cutaneous SCC, including more aggressive and complex cases with intracranial involvement or perineural spread, both as primary treatment and after previous surgery in recurrent cases.